"Isn't it unethical and/or illegal to sell goods that have been sold before as new?"

A key thing that I haven't seen in this discussion is a definition of "new."

If a camera is manufactured, tested as part of the normal manufacturing process, packaged, and sent to a store, I think we'd all agree that at this point it is new. If the camera sits on a shelf in a camera store and is then purchased, we'd agree that it is new. But how about the following scenarios:

1. The seller opens the box, takes the camera out and looks at it to familiarize themselves with everything in the box and then returns the items and puts the box back on the shelf.

2. Same as 1, but the seller adds a lens to the body and a charged battery (not the one from the box) and takes a few shots to verify that the camera is good before selling. They carefully repackage everything the same way it was when the package was opened never broken the seal on the CD package or the manual, and restoring any unwrapped the cable ties so that it doesn't look like they were removed.

3. Same as 1, but the seller adds a lens to the body and takes a few shots and examines them because they want to get familiar with the camera. They carefully repackage everything the same way it was when the package was opened never broken the seal on the CD package or the manual, and restoring any unwrapped the cable ties so that it doesn't look like they were removed.

4. The seller opens the box, takes out the camera and lets a potential buyer handle the body without a charged batter. They carefully repackage everything the same way it was when the package was opened never broken the seal on the CD package or the manual, and restoring any unwrapped the cable ties so that it doesn't look like they were removed.

5. The same as 4, but the seller adds a lens.

6. Same as 4, but the seller adds a lens and a charged battery (not the one from the box) so that the potential buyer can take a few shots.

7. Same as 6, but the buyer steps outside to take those few shots in daylight.

8. Same as 6, but the buyer takes it home and then returns it, without actually paying for anything (they're well known and trusted to return camera or pay for it the next day).

9. Same as 6, but the buyer pays for it, takes it home and then returns it for a refund the next day.

10. The previously untouched box is mailed to someone who opens the box, realizes they bought the wrong thing, and returns it without taking the body or anything else out of the plastic package.

11. The previously untouched box is mailed to someone who takes it out of the box, charges the battery, adds a lens, and takes a few shots before deciding they don't like the body. They carefully repackage everything the same way it was when it was sent out, having never broken the seal on the CD package or the manual, and restoring all the cable ties so that it doesn't look like they were removed.

12. The previously untouched box is mailed to someone who takes it out of the box, charges the battery, adds a lens, and takes a few shots before deciding they don't like the body. They repackage everything imperfectly but securely. When it arrives at the seller, they repackage things again, adding fresh tape to the CD package and the manual package, and restoring all the cable ties so that it doesn't look like they were removed. The package is indistinguishable for when it left the factory and the camera has less than 20 shutter activations.

13. The previously untouched box is mailed to someone who takes it out of the box, charges the battery, adds a lens, and takes a few shots before deciding they don't like the body. They repackage everything imperfectly but securely. When it arrives at the seller, they check that it has all the contents and that everything is packed securely, but it is clear that the package has been opened and repacked.

So, in which of the above scenarios is the camera still "new?" Some would argue that all but situation 13 should be considered new. Others would argue that only situations 1 through 3 would leave the camera "new." Some would say it is "new" until it leaves the premises, but then what about situation 7?